Laser procedure for treatment of presbyopia and other eye disorders

ABSTRACT

A segmented scleral expansion band adapted for implantation within or fastening to a segment of the sclera of an eye lying outside of and adjacent to the ciliary body of the eye, is formed from a number of arcuate segments, curved to match the curvature of the globe of the eye, and joined together at each end to form a complete scleral expansion band. The band is implanted in the sclera of the eye by forming circumferential tunnels, inserting the band segments through the tunnels, and joining the ends of the segments to form a complete scleral expansion band. The scleral expansion band is useful in treating presbyopia and other ocular disorders.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.09/556,143 filed on Apr. 21, 2000, now abandoned which is acontinuation-in-part of U.S. patent application Ser. No. 09/032,830filed on Mar. 2, 1998 (now U.S. Pat. No. 6,197,056), which is acontinuation-in-part of U.S. patent application Ser. No. 08/462,649filed on Jun. 5, 1995 (now U.S. Pat. No. 5,722,952), which is adivisional of U.S. patent application Ser. No. 08/139,756 filed on Oct.22, 1993 (now U.S. Pat. No. 5,489,299), which is a divisional of U.S.patent application Ser. No. 07/913,486 filed on Jul. 15, 1992 (now U.S.Pat. No. 5,354,331).

TECHNICAL FIELD

This invention relates to methods of treating presbyopia, hyperopia,primary open angle glaucoma and ocular hypertension and moreparticularly to methods of treating these diseases by increasing theeffective working distance of the ciliary muscle. The invention alsorelates to increasing the amplitude of accommodation of the eye byincreasing the effective working range of the ciliary muscle.

BACKGROUND

In order for the human eye to have clear vision of objects at differentdistances, the effective focal length of the eye must be adjusted tokeep the image of the object focused as sharply as possible on theretina. This change in effective focal length is known as accommodationand is accomplished in the eye by varying the shape of the crystallinelens. Generally, in the unaccommodated emmettopic eye the curvature ofthe lens is such that distant objects are sharply imaged on the retina.In the unaccommodated eye near objects are not focused sharply on theretina because their images lie behind the retinal surface. In order tovisualize a near object clearly, the curvature of the crystalline lensis increased, thereby increasing its refractive power and causing theimage of the near object to fall on the retina.

The change in shape of the crystalline lens is accomplished by theaction of certain muscles and structures within the eyeball or globe ofthe eye. The lens is located in the forward part of the, immediatelybehind the pupil. It has the shape of a classical biconvex optical lens,i.e., it has a generally circular cross section having two convexrefracting surfaces, and is located generally on the optical axis of theeye, i.e., a straight line drawn from the center of the cornea to themacula in the retina at the posterior portion of the globe. In theunaccommodated human eye the curvature of the posterior surface of thelens, i.e., the surface adjacent to the vitreous body is somewhatgreater than that of the anterior surface. The lens is closelysurrounded by a membranous capsule that serves as an intermediatestructure in the support and actuation of the lens. The lens and itscapsule are suspended on the optical axis behind the pupil by a circularassembly of very many radially directed collagenous fibers, the zonules,which are attached at their inner ends to the lens capsule and at theirouter ends to the ciliary body, a muscular ring of tissue located justwithin the outer supporting structure of the eye, the sclera. Theciliary body is relaxed in the unaccommodated eye and therefore assumesits largest diameter. According to the classical theory ofaccommodation, originating with Helmholtz, the relatively large diameterof the ciliary body in this condition causes a tension on the zonuleswhich in turn pull radially outward on the lens capsule, causing theequatorial diameter of the lens to increase slightly and decreasing theanterior-posterior dimension of the lens at the optical axis. Thus, thetension on the lens capsule causes the lens to assume a flattened statewherein the curvature of the anterior surface, and to some extent of theposterior surface, is less than it would be in the absence of thetension. In this state the refractive power of the lens is relativelylow and the eye is focused for clear vision of distant objects.

When the eye is intended to be focused on a near object, the muscles ofthe ciliary body contract. According to the classical theory, thiscontraction causes the ciliary body to move forward and inward, therebyrelaxing the outward pull of the zonules on the equator of the lenscapsule. This reduced zonular tension allows the elastic capsule of thelens to contract causing an increase in the antero-posterior diameter ofthe lens (i.e., the lens becomes more spherical) resulting in anincrease in the optical power of the lens. Because of topographicaldifferences in the thickness of the lens capsule, the central anteriorradius of curvature decreases more than the central posterior radius ofcurvature. This is the accommodated condition of the eye wherein theimage of near objects falls sharply on the retina.

Presbyopia is the universal decrease in the amplitude of accommodationthat is typically observed in individuals over 40 years of age. In theperson having normal vision, i.e., having emmetropic eyes, the abilityto focus on near objects is gradually lost, and the individual comes toneed glasses for tasks requiring near vision, such as reading.

According to the conventional view the amplitude of accommodation of theaging eye is decreased because of loss of elasticity of the lens capsuleand/or sclerosis of the lens with age. Consequently, even though theradial tension on the zonules is relaxed by contraction of the musclesof the ciliary body, the lens does not assume a greater curvature.According to the conventional view, it is not possible by any treatmentto restore the accommodative power to the presbyopic eye. The loss ofelasticity of the lens and capsule is seen as irreversible, and the onlysolution to the problems presented by presbyopia is to use correctivelenses for close work, or bifocal lenses, if corrective lenses are alsorequired for distant vision.

Certain rings have been used in ocular surgery for various purposes.Rings of flexible and/or elastic material, prepared in situ by fasteningthe ends of strips of the material around the generally posteriorportion of the globe have been used to compress the sclera in certainposterior regions. Supporting rings of metal, adapted to fit the contourof the sclera have been used as temporary supporting structures duringsurgery on the globe. However, none of these known devices have beenused for surgical treatment of presbyopia, and none have been adapted tothe special needs of prosthetic devices used in treating presbyopia.

A scleral band adapted to be fastened to the sclera of the eye in theregion of the ciliary body in order to expand the sclera in that regionand thereby increase the working distance of the ciliary muscle isdescribed in applicant's U.S. Pat. No. 5,354,311, the entire disclosureof which is incorporated herein by reference. The scleral band of thatpatent is manufactured as a single unitary device that is placed on thesurface of the sclera and fastened thereto, e.g., by suturing. Althoughthe band is effective, alternate designs are possible that permitgreater flexibility in installing the scleral band.

Accordingly, a need has continued to exist for a method of treatingpresbyopia that will increase the amplitude of accommodation of thepresbyopic eye, thereby lessening or eliminating the need for auxiliaryspectacle lenses to relieve the problems of presbyopia.

SUMMARY

A method of treating presbyopia and other eye disorders has now beenfound which comprises increasing the effective working distance of theciliary muscle in the presbyopic eye.

Accordingly, it is an object of the invention to provide a method fortreating presbyopia.

A further object is to provide a method for treating presbyopia byincreasing the effective working distance of the ciliary muscle in thepresbyopic eye.

A further object is to provide a method for treating presbyopia byincreasing the radial distance between the equator of the crystallinelens and the ciliary body.

A further object is to provide a method of treating presbyopia byweakening the sclera in the region of the ciliary body.

A further object is to provide a treatment for hyperopia.

A further object of the invention is to provide a treatment for primaryopen angle glaucoma.

A further object is to provide a treatment for ocular hypertension.

A further object is to provide a method for increasing the amplitude ofaccommodation of the eye.

Further objects of the invention will become apparent from thedescription of the invention which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of a scleral expansion band of thisinvention;

FIG. 2 shows an anterior elevational view of the band of FIG. 1;

FIG. 3 shows a posterior elevational view of the band of FIG. 1;

FIG. 4 shows a side view of the band of FIG. 1;

FIG. 5 shows a lateral sectional view of the band of FIG. 2;

FIG. 6 shows a posterior elevation view of another embodiment of thescleral expansion band of the invention which uses pins for fixation;

FIG. 7 shows a lateral sectional view of the band of FIG. 6;

FIG. 8 shows a posterior elevation view of another embodiment of thescleral expansion band of the invention which uses tangentiallyextending fixation pins; and

FIG. 9 shows a lateral sectional view of the band of FIG. 8. and

FIG. 10 shows a method for treating presbyopia and other eye disorders.

DETAILED DESCRIPTION

This invention is based on a theory of presbyopia different from theclassical theory of Helmholtz. Although the scope of the invention isnot to be bound or limited by the inventor's theory, it is theinventor's view that the presbyopic loss of accommodation is due todecreased working distance of the ciliary muscle. This theory isdescribed in more detail in U.S. Pat. No. 5,354,331, referenced aboveand incorporated herein by reference. Consequently, according to theinvention, presbyopia is treated by increasing the effective workingdistance of the ciliary muscle. This is accomplished by increasing thedistance between the ciliary muscle and the lens equator by increasingthe diameter of the sclera in the region of the ciliary body.

This invention is based on a theory of presbyopia, developed by theinventor, regarding the cause of the loss of amplitude of accommodationthat constitutes presbyopia. According to this view, accommodation inthe non-presbyopic eye is not due to relaxation of the lens and capsulewhen the zonular tension is relaxed as a result of the contraction ofthe ciliary body. On the contrary, the contraction of the ciliary body,exerts a tension on the zonular fibers that in turn actually results inan increase in the equatorial diameter of the lens. However, theincreased zonular tension causes a decrease in the peripheral volume ofthe lens that in turn results in a corresponding increase in the centralvolume of the lens. These regional volume changes in the lens areresponsible for the change in optical power of the lens. This viewdiffers from all previous theories of the mechanism of accommodation andits loss in presbyopia, in particular from Tscherning's theory whichrequired the vitreous and attributed presbyopia to an enlargement of thenucleus of the lens. From the inventor's point of view, the differencebetween the change in the central anterior radius of curvature and thechange in the central posterior radius of curvature which occurs inaccommodation is explained by the force distribution generated by thezonular attachment to the lens and is not dependent on the topographicalthickness of the elastic capsule of the lens, the vitreous, or pressurechanges which occur between the anterior and posterior chambers,explanations which have been proposed in the prior art. According to thetheory of this invention, presbyopia results when the distance betweenthe ciliary body and the equator of the lens and its capsule becomesless with age as a result of the normal growth of the lens. The lens,being of ectodermal origin, continues to grow throughout life, albeitslowly. The rate of increase of the equatorial diameter is approximately0.02 millimeters per year. On the other hand, the dimensions of thescleral shell of the eye, which is of mesodermal origin, do not increasesignificantly after about age 13 in a normally emmetropic, hyperopic ormyopic eye. Consequently, the radial distance between the equator of thelens and capsule and the ciliary body, i.e., the distance measuredperpendicularly to the optical axis in the plane of the ciliary body,decreases throughout life. It is well known in muscle physiology that asthe length of the effective range of pull of a muscle, i.e., itseffective working distance, is reduced, its effective force is reducedin a linear fashion. Since the distance between the ciliary body and thelens equator is decreasing throughout life, it is to be expectedaccording to the theory of the invention that there would be acorresponding linear decrease in the amplitude of accommodation, asobserved (Alpern, M., in The Eye, H. Dayson, Ed., Academic Press, NewYork, 1969, pp.237-238), which would lead eventually to presbyopia.

According to the invention presbyopia is treated by increasing theeffective working distance of the ciliary muscle. A number of proceduresare available to the surgeon which can accomplish this increase ineffective working distance.

A straightforward method of increasing the effective working distance ofthe ciliary muscle is to increase the distance between the equator ofthe crystalline lens and the inner diameter of the ciliary body in thepresbyopic eye. This increased distance restores, at least to someextent, the distance through which the muscles of the ciliary body cancontract, and thereby restores their ability to exert force on the lensand change its shape to accomplish accommodation. Any method thatincreases the radial distance between the lens and the ciliary body iseffective in the method of this invention.

The effective working distance of the ciliary muscle can also beincreased by shortening the zonules that connect the ciliary muscle tothe equator of the crystalline lens. Similarly, procedures that shortenthe body of the ciliary muscle itself or move its insertions in thescleral spur and the choroid can be employed to increase the effectiveworking distance of the muscle. Finally, procedures that arrest thegrowth of the lens can stop the steady loss of amplitude ofaccommodation, and such procedures are considered as fully within thescope of this invention.

It is preferred to increase the lens-ciliary body radial distance byincreasing the diameter of the sclera in the region of the ciliary body.Any method that can accomplish such an increase in the diameter of thesclera is considered to fall within the scope of the invention.

A preferred method of increasing the diameter of the sclera in theregion of the ciliary body is to fasten to the sclera in that region arelatively rigid band having a diameter slightly larger than the sectionof the globe of the eye in the region of the ciliary body. In this waythe sclera in that region is stretched and expanded so that the diameterof the circle describing the intersection of the plane of the ciliarybody with the sclera is slightly increased. The ciliary body, locatedimmediately inside the globe and attached to the sclera in this expandedregion is thereby also increased in diameter.

Thus, the scleral expansion band of the invention adapted for fasteningto the sclera of a human eyeball in the region of the ciliary bodycomprises an anterior rim and a posterior rim, the anterior rim beingsized to lie adjacent to the anterior portion of a segment of the scleraof the human eyeball overlying the ciliary body of the eyeball and theposterior rim being sized to lie adjacent the posterior portion of thescleral segment, and rigid structural means extending between the rimsand spacing said rims apart so that the anterior rim will lie outsidethe anterior portion of the scleral segment when the posterior rim liesoutside the posterior portion of said scleral segment. The anterior rim,the posterior rim and/or the rigid structural means connecting the rimshas a diameter greater than the exterior diameter of the scleral segmentadjacent thereto.

Thus, the scleral expansion band of the invention is adapted to befitted to the sclera of the globe in the region of the ciliary body. Theband will have, at least in part, a diameter slightly greater than thatof the sclera at the location where it is to be attached. When the bandis fitted to the sclera and firmly attached thereto it will exert aradially outward tension on the sclera which expands the sclera and theunderlying ciliary body. The scleral expansion band of the invention maybe fastened to the sclera by any conventional surgical method. Forexample, the band may be a smooth solid band and be sutured to thesclera with sutures passing around the body of the band. A preferredband of the invention is provided with suturing holes through which thesutures may be passed. The band may also be fastened with conventionalsurgical staples or clips as are well known in the ocular surgery art.The band may be provided with projections or cut-out portions that canbe used as anchoring points for sutures. The band may also be providedwith projecting pins or the like which are inserted into or under thesclera to position the band and exert the appropriate radially outwardtension. These pins may extend in an anterior and/or a posteriordirection from the band, and may project from one or both rims of theband or from the web portion connecting the rims. The pins may alsoproject in a generally tangential direction from the rims or the insideof the web and be provided with sharpened tips or the like whereby theywill penetrate the sclera when the band is rotated and cause the sclerato be firmly fixed to the band and expanded. The band may also beadhesively fastened to the sclera with any physiologically acceptablesurgical adhesive. A preferred surgical adhesive is a surgical gradecyanoacrylate adhesive. Mussel adhesive protein may also be used as asuitable adhesive.

A preferred embodiment of the scleral expansion band of the invention isillustrated in FIGS. 1-5. The band 102 has a low frustoconical shape andhas a posterior rim 106 and an anterior rim 108, with a web 104extending between the rims. The band may be provided with one or moreholes 110 to assist in suturing the band to the sclera. The anterior rim106 and the posterior rim 108 are both of generally circular shape. Thetaper in the diameter of the band is preferably selected in anindividual case to fit the globe in the region of the ciliary body.Accordingly, a preferred band has a low frustoconical having a circularbase about 20 millimeters in diameter. The radial thickness of the bandwill be determined by the rigidity required in the band and the strengthof the material from which it is made. Typically the radial thickness ofthe band will be about 0.1 to 0.75 millimeters depending on the rigidityof the substance used to make the band. The diameter of the anterior rim106 of the band will be determined by the size of the globe in thepatient to be treated. Accordingly, different sizes of band areavailable wherein the lesser diameter ranges from about 14.5 millimetersto about 18.0 millimeters in 0.25 millimeter increments. The axial widthof the band will typically be about 2 millimeters.

An alternate embodiment of the scleral expansion band of the inventionadapted to be fixed to the sclera by pins is illustrated in FIGS. 6 and7. In this embodiment posterior pins 112 are fixed to the band andextend therefrom in a posterior direction while anterior pins 114 extendin an anterior direction.

Another embodiment of the band of the invention using interiortangentially-directed pins 114 is illustrated in FIGS. 8 and 9. Thisembodiment can be easily installed by placing it in position on theglobe and rotating it to cause the tangential pins to penetrate thesclera and fasten it firmly to the band. This embodiment can be easilyremoved at a later time by merely rotating it in the opposite directionto withdraw the pins from the sclera.

The scleral expansion band of the invention is made of a material thatis sufficiently rigid to exert a force on the sclera sufficient toproduce the radial expansion required by the method of the invention andthat is physiologically acceptable for long-term implantation or contactwith the ocular tissues. Such materials are well-known in the surgicalart and include suitable metals, ceramics, and synthetic resins.Suitable metals include titanium, gold, platinum, stainless steel,tantalum and various surgically acceptable alloys, and the like.Suitable ceramics may include crystalline and vitreous materials such asporcelain, alumina, silica, silicon carbide, high-strength glasses andthe like. Suitable synthetic resins include physiologically inertmaterials such as poly(methyl methacrylate), polyethylene,polypropylene, poly(tetrafluoroethylene), silicone resins and the like.The band may also be made of composite materials incorporating asynthetic resin or other matrix reinforced with fibers of high strengthmaterial such as glass fibers, boron fibers, carbon fibers, aluminafibers or the like. Thus, the band may be made of glass-fiber-reinforcedepoxy resin, carbon fiber reinforced epoxy resin, carbon fiberreinforced carbon (carbon-carbon), or the like. A preferred material issurgical grade poly(methyl methacrylate).

The scleral expansion band of the invention may be manufactured by anyconventional technique appropriate to the material used, such asmachining, injection molding, heat molding and the like.

The scleral expansion band may also be made in a plurality of parts thatcan be assembled prior to use or may be installed separately to form acomplete band. The band may be adjustable in circumference. For examplethe band may be formed from a strip of material, e.g., metal orsynthetic resin, with overlapping ends so that the ends may slide pastone another thereby adjusting the circumference of the band. The lengthof the overlap may be adjusted, for example, by means of a tangentialscrew mechanism to adjust the circumference of the band and thereby theamount by which the sclera is expanded.

In practicing the method of the invention, the surgeon locates theproper region of the sclera to be expanded by measuring a distance of1.5 millimeters posterior of the limbus. At this point the diameter ofthe circle of sclera surrounding the ciliary body is carefully measuredand a band is selected having a minor diameter about 0.5 millimetergreater than the measured diameter. A circular incision is made throughthe conjunctiva completely around the globe at the selected region andthe conjunctiva and Tenon's capsule are reflected to expose thesubstance of the sclera. For greatest accuracy in positioning thescleral expansion band, the diameter of the sclera as exposed by thereflection of the conjunctiva and Tenon's capsule is measured at a point1.5 mm posterior to the limbus. Alternatively the size of sclera can bemeasured before the conjunctiva is incised. The band is then placed onthe surface of the globe and sutured thereto preferably with interruptedstitches as conventional in ophthalmological surgery. In order tofacilitate suturing the band to the sclera, the band may be perforatedwith holes. For example, a total of sixteen holes may be placedequidistant around the band.

It is also possible to expand the sclera in the region of the ciliarybody by positioning a band within or just inside the sclera, the bandhaving a diameter just greater than the natural diameter of theoverlying tissue. In this way the interior band will expand theoverlying tissue and produce the desired result of increasing theeffective working distance of the ciliary muscle.

Other methods for increasing the diameter of the sclera in the region ofthe ciliary body may also be used in the treatment of presbyopiaaccording to the invention. The sclera itself is a tough strong capsulecomprised largely of collagen and held in a rigid state of tension bythe internal ocular pressure (IOP). If the sclera is weakened in thearea adjacent to the ciliary body, the IOP will cause that portion ofthe sclera to bulge outward, thereby increasing the diameter of theciliary body and increasing the distance of the ciliary body from thelens. Any method of weakening the structure of the sclera is suitable.For example enzymatic degradation of the collagen by collagenase may beemployed. The collagenase may be carefully injected in to theappropriate region of the sclera or may be applied topically. Equivalentenzymes or other chemical treatments that weaken the collagen of thesclera can also be used. Certain antimitotic drugs such as mitomycin areknown to cause a softening of the sclera (scleromalacia), and thesedrugs can be applied to the region of the sclera adjacent to the ciliarybody, either topically or by injection, to effect the desired weakeningof the sclera. Other antimitotic pharmaceutical agents, e.g.,methotrexate, azaribine, 6-mercaptopurine, 5-fluorouracil, daunorubicin,doxorubicin, cytarabine, the vinca alkaloids and the like, can also beapplied to the sclera to weaken it and permit it to be expanded by theintraocular pressure.

Alternatively, the sclera in the region of the ciliary body may beweakened by surgical means. The sclera may be thinned or weakened by thesurgical removal of a portion of its collagenous substance, as, forexample by ablating a portion of the thickness of the sclera. Thisthinning can be accomplished by paring or by abrading the surface or byablating the surface with laser irradiation. The sclera can also beweakened by incisions carefully placed at appropriate angles in theregion overlying the ciliary body. The diameter of the sclera overlyingthe ciliary body can also be increased by making a complete periglobularincision and grafting into the incision appropriate tissue and/orphysiologically acceptable structural material to increase thedimensions of the sclera. Thus an artificial scleral alloplant made ofpurified human collagen may be engrafted into such an incision. Otherknown biocompatible materials, e.g., poly(ethylene terephthalate), thatare conventionally used in the construction of prosthetic devices mayalso be used for engrafting into such an incision. It is also possibleto excise a small strip of sclera from the region overlying the ciliarybody and replace it with a scleral alloplant as described above toprovide an appropriate increase in the diameter of this region.

Alternatively the sclera in the region overlying the ciliary body can beweakened by irradiation with a laser beam to decompose partially thecollagen fibers. Suitable lasers include those conventionally used inocular surgery such as carbon dioxide lasers, helium-neon lasers,helium-cadmium lasers, argon ion lasers, krypton ion lasers, xenonlasers, nitrous oxide lasers, iodine lasers, holmium dopedyttrium-aluminum garnet (YAG) lasers, excimer lasers, chemical lasers,harmonically oscillated lasers, dye lasers, nitrogen lasers, neodymiumlasers, erbium lasers, ruby lasers, titanium-sapphire lasers, diodelasers and the like. Any irradiative treatment with ionizing ornon-ionizing radiation that weakens the sclera may be used. For exampleirradiation with electrons, protons, or x-rays and the like, orirradiation with ultrasonic waves or the like can be used. Thermalburning and/or scarring in the appropriate area may also be used toinduce an enlargement of the sclera in the area adjacent to the ciliarybody.

Treatments designed to weaken the sclera in the region overlying theciliary body can also be combined with application of the scleralexpansion band of the invention. For example, the sclera can be treatedwith collagenase, mitomycin, or other antimitotic agent, as describedabove and the scleral band subsequently applied and fastened to thesclera. The band itself, its components and/or the sutures may also becoated or impregnated with the sclera-weakening agents whereby they cancome into contact with the sclera and exercise their effect when theband is applied. In some cases the band may be later removed to leavethe patient with a suitably expanded sclera.

Just as the distance between the ciliary body and the equator of thelens can be increased by expanding the sclera and ciliary body, thedistance can be maintained and the progress of presbyopia arrested bystopping the growth of the crystalline lens. While such a treatmentcannot reverse the course of presbyopia, it can arrest the progress ofthe symptoms, and is appropriate for treatment of patients in whom thepresbyopia has not progressed very far. The growth of the lens can bearrested by administration of pharmaceutical compounds which stop celldivision and growth. For example, colchicine can be administered toprevent cell division, thereby stopping the growth of the lens.Conventional antimitotic drugs may also be used to arrest the growth ofthe lens. Such drugs are well known and include, for example,methotrexate, azaribine, 6-mercaptopurine, 5-fluorouracil, daunorubicin,doxorubicin, cytarabine, the vinca alkaloids and the like. Such drugsmay be applied topically or by injection into the appropriate structureof the eye where they will come into contact with the lens and exercisetheir pharmacological activity. If the drugs are sufficiently free ofside effects, they may also be administered systemically, either bymouth or parenterally. The growth of the lens may also be arrested byphysical treatments directed at the newly forming cells in theepithelium of the lens, particularly in the equatorial region of thelens. Treatments that prevent further division of the cells areappropriate for preventing further lens growth. Thus, the epithelialcells may be heated by laser radiation or ultrasonic irradiation, orinactivated by laser irradiation with a laser capable of directlydisrupting chemical bonds within the structures of the cells. Sharplyfocused laser beams or irradiation with microscopic diode laserspositioned close to the equator of the lens are suitable for applyingthis radiation. Irradiation with electrons, protons, x-rays or the likemay also be used to stop the further division of the epithelial cells ofthe lens. These treatments should be directed only to the portion of thelens structures that are composed of cells capable of dividing andshould not be directed toward the substance of the lens where they mightprovoke the formation of cataracts.

Surgical methods that work more directly on the ciliary muscle may alsobe used to increase the effective working distance of the muscle. Thebody of the muscle itself may be shortened, for example by scarringinduced by irradiation with suitable laser beams or beams of ionizing ornon-ionizing radiation such as ultrasound or electron or proton beams orx-rays. The effective working range of the muscle may also be increasedby moving its insertions to increase the distance between them. Theciliary muscle is inserted anteriorly into the scleral spur andposteriorly into the choroid. Treatment of either of these insertions tocause them to move apart from the complementary insertion will increasethe effective working range of the ciliary muscle and improve theamplitude of accommodation according to the invention. Selectivescarring of adjacent tissue planned to cause retraction of eitherinsertion of the ciliary muscle is effective to accomplish this result.The scarring can be accomplished by thermal or radiative treatment ofthe tissue by the means and methods generally outlined above.

The methods of the invention which increase the amplitude ofaccommodation may also be of benefit in treatment of hyperopia incertain patients. Some youthful hyperopes can achieve relatively normalvision by compensating for their hyperopia through the naturalaccommodative ability of the eye. However, as this ability declines withage, they find that it becomes more difficult to attain normal vision bythis process, and they begin to experience headaches and other symptoms,even at an age somewhat less than usual for the onset of presbyopia.Evidently, increasing the amplitude of accommodation by the method ofthis invention would be useful in restoring the ability of thesepatients to compensate for their hyperopia.

The method of this invention also has utility in the treatment ofprimary open-angle glaucoma, which shows a correlation with age incertain individuals. It has been found that, in general, IOP exhibits alinear increase with increasing age. (Armaly, M.F., On the distributionof applanation pressure I. Statistical features and the effect of age,sex, and family history of glaucoma, Archives of Ophthalmology, Vol. 73,pp. 11-18 (1965).) Among the general population is found a group ofindividuals who develop abnormally high intraocular pressures as aresult of primary open angle glaucoma, a disease which is one of themost prevalent causes of blindness in the world. According to the theoryof this invention, the linear increase in IOP with age is a directresult of the decrease in distance between the lens equator and theciliary muscle and the resulting linear decrease in the effective pullof the ciliary muscle. Since the ciliary muscle inserts into thetrabecular meshwork, the decrease in pull will decrease the size of thetrabeculum and/or the drainage pores and result in a linear increase ofintraocular pressure with age. In this view, the patients who developprimary open angle glaucoma may have a congenital predilection tonarrower pores and/or smaller trabecular meshwork, so that when theability of the ciliary muscle to exert force declines, after the age of40 or thereabouts, they tend to develop excessively elevated IOP.

The method of the invention which increases the effective workingdistance of the ciliary muscle, and thereby increases the force that itcan exert when it contracts, restores the level of force which theciliary muscle exerts on the trabecular meshwork to a valuecharacteristic of a more youthful eye. In this way it is expected thatthe tendency of an eye that is disposed to develop primary open angleglaucoma as it ages would be overcome and the onset of this diseasewould be prevented or at least postponed.

The ability of the ciliary muscle to exert tension on the lens by meansof the zonules can also be increased by shortening the zonules, aprocedure which increases the effective working range of the ciliarymuscle. This shortening can be produced by heating the zonules byultrasonic irradiation or laser irradiation. The zonules may also betreated with electrons, protons, x-rays and the like which may causechanges in the structure of the zonules resulting in shortening. Theshortening of the zonules may also be brought about by application ofchemical compounds that act to cause a shrinkage of the collagenouszonules.

The invention will be illustrated by the following examples which areintended for illustration only and are not to be interpreted as limitingthe claims.

EXAMPLE 1

This example illustrates the feasibility of increasing the diameter ofthe ciliary body by suturing an external band to the sclera.

Human cadaver eyes were selected for experimentation. The diameter ofthe sclera was measured using a shadow graph at distances of 1.5millimeters and 3.5 millimeters from the limbus. The diameters werefound to be 16.2 mm and 20 mm respectively. Bands were made from medicalgrade poly(methyl methacrylate) having a low frustoconical shape and aradial thickness of 0.5 mm. The internal diameter of the larger(posterior) side was 20 mm, and the smaller (anterior) diameters variedfrom 14.5 mm to 18.0 mm in 0.25 mm steps. A band was selected having amajor diameter of 20 mm and a minor diameter of 18.0 mm. The band wasplaced on the sclera of a human cadaver eye so that the 18.0 mm diameterend of the band was 1.5 mm from the limbus and the 20 mm diameter endwas 3.5 mm from the limbus. The band was sutured through the holes with16 interrupted 6-0 polyester (Mersilene, Ethicon, Inc.) stitches to thesclera. This resulted in a clearly observable stretching of the sclerain the region of the ciliary body. The pupil became dilated by about 1.5mm. Since the iris inserts into the ciliary body, the pupillary dilationdemonstrated that the induced scleral stretching was also moving theciliary body outward, thereby increasing its diameter and its distancefrom the equator of the lens.

EXAMPLE 2

This example illustrates the treatment of presbyopia in patients.

Following informed consent, six presbyopic patients with otherwisenormal eyes, except for minimal refractive errors, had scleral expansionbands of the invention sutured to the sclera in the region of theciliary body. Their age ranged from 47 to 60 years, there were threemales and three females, and their preoperative amplitude ofaccommodation varied from 1.3 to 2.7 diopters. The ophthalmologicalexamination including biomicroscopy was normal. Following localinfiltration into the conjunctive with prilocaine HC1 for injection(Citanast (Astra), 40 mg/ml), a 360 degree limbal based peritomy wasperformed and the sclera was cleaned of Tenon's capsule. Using verniercalipers, a distance of 1.5 mm posterior to the limbus was measured fromthe limbus and the scleral diameter was measured at that location. Aband of the type made in Example 1 was selected having a minor diameterof from 0.5 mm to 1.5 mm greater than the measured diameter of thesclera. The band was sutured to the sclera with 16 interrupted 6-0polyester (Mersilene, Ethicon, Inc.) stitches. The patients were givenantibiotic-steroid drops to use for five days. Postoperatively, thepatients were followed daily for five days and then weekly. The resultsare presented in Table 1 below.

TABLE 1 Preoperative and Postoperative Amplitude of AccommodationPreoperative Postoperative Near Amplitude of Near Amplitude of PatientAge Point Accommodation Point Accommodation No. (yr) Sex (cm) (diopters)(cm) (diopters) 1 55 M 75 1.3 9 11.1 2 50 F 45 2.2 10 10.0 3 47 F 37 2.716 6.25 4 56 M 56 1.7 9 11.1 5 60 F 38 2.6 12 8.3 6 46 M 40 2.5 17 5.8

FIG. 10 shows a method for treating presbyopia and other eye disorders.As shown in FIG. 10, at least a portion of the sclera in a patient's eyeis irradiated, thereby weakening the sclera, at step 1002. The abilityof the ciliary muscle of the patient's eye to exert tension is increasedat step 1004. The working distance of the ciliary muscle of thepatient's eye is increased at step 1006. During this process, thethickness of the sclera in the region of the ciliary body of the eye isreduced without forming an opening completely through the sclera.

The invention having now been fully described, it should be understoodthat it may be embodied in other specific forms or variations withoutdeparting from its spirit or essential characteristics. Accordingly, theembodiments described above are to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than the foregoing description,and all changes which come within the meaning and range of equivalencyof the claims are intended to be embraced therein.

I claim:
 1. A method of operating a laser to treat one of presbyopia,hyperopia, primary open angle glaucoma, and ocular hypertension, themethod comprising: irradiating at least a portion of an eye to increasean ability of a ciliary muscle in the eye to exert tension, whereinirradiating at least the portion of the eye increases an effectiveworking distance of the ciliary muscle; wherein irradiating at least theportion of an eye comprises reducing a thickness of a sclera of the eyein a region of a ciliary body of the eye without forming an openingcompletely through the sclera.
 2. The method of claim 1, whereinirradiating at least the portion of the eye comprises using laserirradiation to shorten the ciliary muscle.
 3. The method of claim 1,wherein irradiating at least the portion of the eye comprises usinglaser irradiation to shorten one or more zonules, the ciliary musclecapable of exerting tension on a lens of the eye using the one or morezonules.
 4. The method of claim 1, wherein irradiating at least theportion of the eye comprises using at least one of: a carbon dioxidelaser, a helium-neon laser, a helium-cadmium laser, an argon ion laser,a krypton ion laser, a xenon laser, a nitrous oxide laser, an iodinelaser, a holmium doped yttrium-aluminum garnet (YAG) laser, an excimerlaser, a chemical laser, a harmonically oscillated laser, a dye laser, anitrogen laser, a neodymium laser, an erbium laser, a ruby laser, atitanium-sapphire laser, and a diode laser.
 5. The method of claim 1,wherein irradiating at least the portion of the eye comprises weakeningthe sclera and increasing a diameter of the sclera overlying the ciliarybody.
 6. The method of claim 5, wherein irradiating at least the portionof the sclera comprises abrading at least a portion of the sclera withlaser irradiation.
 7. The method of claim 5, wherein irradiating atleast the portion of the sclera comprises ablating at least a portion ofthe sclera with laser irradiation.
 8. The method of claim 5, whereinirradiating at least the portion of the sclera comprises incising atleast a portion of the sclera with laser irradiation.
 9. The method ofclaim 5, wherein irradiating at least the portion of the scleracomprises incising at least a portion of the sclera at select angleswith laser irradiation.
 10. The method of claim 5, wherein irradiatingat least the portion of the sclera comprises partially decomposingcollagen fibers in at least a portion of the sclera.
 11. A method,comprising: weakening a sclera of an eye using laser irradiation toincrease an ability of a ciliary muscle in the eye to exert tension,wherein weakening the sclera of the eye increases an effective workingdistance of the ciliary muscle; wherein weakening the sclera of the eyecomprises reducing a thickness of the sclera in a region of a ciliarybody of the eye without forming an opening completely through thesclera.
 12. The method of claim 11, wherein weakening the scleracomprises abrading at least a portion of the sclera with the laserirradiation.
 13. The method of claim 11, wherein weakening the scleracomprises ablating at least a portion of the sclera with the laserirradiation.
 14. The method of claim 11, wherein weakening the scleracomprises incising at least a portion of the sclera with the laserirradiation.
 15. The method of claim 11, wherein weakening the scleracomprises incising at least a portion of the sclera at select angleswith the laser irradiation.
 16. The method of claim 11, whereinweakening the sclera comprises partially decomposing collagen fibers inat least a portion of the sclera.
 17. A method, comprising: irradiatingat least a portion of a sclera of an eye to increase an ability of aciliary muscle in the eye to exert tension; wherein irradiating at leastthe portion of the sclera comprises reducing a thickness of the sclerain a region of a ciliary body of the eye without forming an openingcompletely through the sclera.
 18. The method of claim 17, whereinirradiating at least the portion of the sclera comprises at least one ofabrading, ablating, and incising at least a portion of the sclera withlaser irradiation.
 19. The method of claim 17, wherein irradiating atleast the portion of the sclera comprises incising at least a portion ofthe sclera at select angles with laser irradiation.
 20. The method ofclaim 17, wherein irradiating at least the portion of the scleracomprises partially decomposing collagen fibers in at least a portion ofthe sclera.